Hip replacement procedures involve the replacement of the hip joint formed by the head of the femur and the acetabulum of the pelvic bone. Hip replacement procedures include the preparation of the femur for receipt of a femoral component and preparation of the acetabulum to receive an acetabulum component. The two components engage together to replace the hip joint.
FIG. 1 illustrates a hip replacement implant 100 positioned within a patient. The implant 100 includes the femoral component 101 that is attached to the femur 110, and an acetabular component 102 that is attached to the acetabulum 111 in the pelvic bone 112. The femoral component 101 includes a head 103 that seats within a receptacle of the acetabular component 102. This replacement joint replicates the hip joint and provides for pivoting movement of the femur 110 relative to the pelvic bone 112.
The femoral component 11 is implanted into the femoral canal of the femur 100. After implantation, bone growth occurs with the femoral component to secure its position within the femur 110.
In some instances, it is necessary to remove the femoral component 101 from the femur 110 during a revision procedure after implantation and bone growth. FIG. 2A illustrates one situation in which the femoral component 101 is fractured into two sections while implanted in the femur 110. FIG. 2B illustrates the sections 101a, 101b after removal from the patient. Section 101a is referred to as a proximal section and section 101b is referred to as a distal section.
The sections 101a, 101b are required to be removed from the femur 110. The proximal section 101a is exposed above the proximal end of the femur 110 and removed more using various instrumentation. The distal section 101b is recessed within the femur 110 and is generally more difficult to access and remove.
Current methods of removing the distal section include trephine reamers that are inserted over the distal section. The trephine reamers are rotated and have cutting teeth along a distal end that cut the femur to remove the distal section. The teeth are closely spaced together along the distal end. During cutting, the removed bone accumulates in the intermediate space between the teeth. Because of the closeness of the teeth, the intermediate spaces quickly fill with the removed bone and interfere with the teeth thus preventing further bone removal. This requires the surgeon to replace the trephine reamer numerous times during removal of the distal section. During a procedure, a surgeon may be required to use a large number of separate trephine reamers to cut enough bone to remove the femoral component. The process of repeatedly replacing the trephine reamers is burdensome for the surgeon and adds cost to the procedure.